1. Field of the Invention
This technology relates to oil and gas wells, and in particular to pipe connectors within the wells.
2. Brief Description of Related Art
Typical oil and gas wells include strings of pipe that extend into the well in conjunction with drilling, casing, and production operations. These strings of pipe generally consist of discrete pipe segments that are joined together by pipe connectors as the pipe is run into the well. The pipe connectors may be threaded, with adjacent connectors having male and female threads configured to engage and join the pipe. Generally, the pipe end having the male thread is known as the pin, and the pipe end having the female thread is known as the box. When joining the pipe segments, it is desirable to limit circumferential movement between the connectors so that the connectors remain firmly attached. To limit such circumferential movement, a lock key may be employed.
Some known lock keys require corresponding grooves in the pin and the box that align when the pin and the box are threaded together. The key is then inserted into the aligned grooves to prevent relative circumferential movement between the pin and the box. However, many pipe connectors that are threaded together cannot be repeatedly assembled to the same relative angle to each other due to manufacturing variations in the thread, as well as changes to the thread of connectors previously used under load. This is because the pipe connectors must be fully torqued to ensure that the joint properly seals, regardless of the relative positions of the locking grooves on the pin and box.
Additionally, some threaded connectors have small overall wall thickness (e.g., subsea drill pipe and casing), thereby requiring a key that is low profile. Furthermore, under some circumstances there is not enough space surrounding the pipe connectors to incorporate large external mechanisms to drive locking pins or keys into place, as required for many types of locking keys.